12v 7ah sealed lead acid battery charger circuit , which is best???

[mohandes]

Hi all guru and my friend
look this pics and tell me about them and guide me.
first http://www.eleccircuit.com/the-most-...cuit-by-lm317/:


second : http://www.vt52.com/diy/myprojects/o...er/charger.htm


third :http://www.sentex.ca/~mec1995/gadgets/labc.htm

forth : http://obrazki.elektroda.pl/5383882700_1371186720.jpg

fifth : http://www.aaroncake.net/circuits/ch...owcomments=all


and finall: http://homemadecircuitsandschematics...c-battery.html



Or every one have circuit better of above put it here.

say me which is good that i make it.

cheers and regards

[Tepco]

Just about any is good, there are better ones too, sealed batteries require bit specific charging, constant current up to some preset voltage (see battery manufacturer data for recommendation, like 13.6-13.8V), then charge is held at that voltage. LM317 circuit is “classic” just be warned, lot of heat will be dissipated, constant current is actually internal current limit of LM 317, good heatsink is needed. Using ordinary resistor -diode charging like for NiCd accu or ordinary car battery style charging can ruin battery and significantly reduce lifetime.

[mohandes]

thanks tepco

but which is better for 12v 7ah?i think finall picture is the best?but how can i adjust the pot 1kohm?
this pot series to 470 ohm and my means that : what size is together, for example 1300ohm good??how can i calc it for i have 700ma or 800ma?
thanks

[Tepco]

In this last circuit, resistor R1 adjust output current, 0.5R value in combination of some 600mV B-E junction of Q1 will produce around 1.2A, actual value may depend on Q1, if you need less current increase R1, with 1R you will have half of that etc. This is charging current, it will gradually fall when battery is nearly completely charged. R5 adjust output voltage needed to be reached when battery is completely charged, from then, circuit acts as a voltage source to maintain charge. This voltage is usually around 13.8V, but may vary with battery type and manufacturer from 13.6 to 14.5V check data for battery type you use for optimal performance. Manufacturers usually have some recommendations or application paper on their websites, find them. Adjust this voltage without battery connected, if you set too low, battery will not be charged to full capacity, if too high, this may damage battery and slightly reduce lifetime.

[mohandes]

In this last circuit, resistor R1 adjust output current, 0.5R value in combination of some 600mV B-E junction of Q1 will produce around 1.2A, actual value may depend on Q1, if you need less current increase R1, with 1R you will have half of that etc. This is charging current, it will gradually fall when battery is nearly completely charged. R5 adjust output voltage needed to be reached when battery is completely charged, from then, circuit acts as a voltage source to maintain charge. This voltage is usually around 13.8V, but may vary with battery type and manufacturer from 13.6 to 14.5V check data for battery type you use for optimal performance. Manufacturers usually have some recommendations or application paper on their websites, find them. Adjust this voltage without battery connected, if you set too low, battery will not be charged to full capacity, if too high, this may damage battery and slightly reduce lifetime.

thanks man

just pot should be 1k ohm.
if you check it , it is similar to last pics that i am send.

which is better i make?


OR

[Tepco]

upper one is for 12V and lower is for 6v, not to go into details, find lm317 datasheet, answer is on the first page.